Method for determining the efficiency of laundry machines



July 15 1924. 1,501,856

R. L. LEE

METHOD FOR DETERMINING THE EFFICIENCY OF LAUNDRY MACHINES Filed Aug. 6, 1923 4 1772/2217? HALPH LL55- gw llvnk.

Patented July 15, 1924.

UNITED STATES PATENT ounce- RALPH L. LEE, OF DAYTON, OHIO. ASSIG-NOR TO DELCO-LIGI-IT COMPANY, OF DAYTQN,

OHIO, A. CORPORATIGN OF DELAWARE.

METHOD FOR DETERMINING THE EFFICIENCY OF LAUNDRY MACHINES.

Application filed August e, 1923. Serial No. 655,915.

To all whom it may concern:

Be it known that I, RALPH L. LEE, a citizen of the United States of America, residin at Dayton, county of Montgomery, and tate of Ohio, have invented certam new and useful Improvements in Methods for Determining the Efficiency of Laundry Machines, of which the following is a full, clear, and exact description.

This invention relates to laundry apparatus, and includes among its objects, the provision of a simple and accurate method of determining the relative cleansing ability 'of different types of laundry machines.

This method includes soiling artificially a sample of white cloth, and then determining its cleanliness before and after washing ina certain machine by photometric measurements, using an unsoiled sample of preferably the same piece of goods to represent one hundred percent cleanliness. The difference in cleanliness before and after washing is used as a measure of the cleansing ability of the machine selected for test, and serves as a basis for judging the relative cleansing ability of various washing machines.

Other and further objects of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of one form of the present invention is clearly shown.

In-the drawings:

Fig. 1 represents a specimen comprising a piece of cloth 100 per cent clean;

Fig. 2 represents a specimen after bein treated with a standard dirt solution an before being washed; i

Fig. 3 represents a specimen after being washed by a laundry machine of a certain y Fig. 4 represents a specimen after being washed by a laundry machine of another 45 ty e; and

ig. 5 is a diagrammatic view showing the method 'of testing the specimens to determine the percentage of cleanliness.

The specimens. A satisfactory material for the specimens rinsed in a tub of clean, cold water, after which they are wrung out and hung up to dry. The specimens, when thoroughly dry, are ready to be impregnated with a dirt solution. The specimens can be used but one time, inasmuch it is impossible to remove all the dirt solution therefrom without changing the quality of the specimen.

It is desirable, for the purposes of this method of test, to impregnate the specimens with a dirt solution that will not quickly wash out but which may be substantially removed from the specimens by subjecting them to a washing operation for a period of time equal to that usually required by a laundry machine for washing a tub of soiled laundry. I

The dirt solution, in order to closely approximate the type of dirt usually present on soiled laundry, includes a form of finely divided carbon mixed with a binder and a volatile carrier or spreader, the binder being an oil for attaching the carbon particles.

to the cloth, and the volatile carrier for distributing the carbon and binder evenly.

.The carbon and binder may be provided by mixing lamp black and an oil such as olive oil, castor oil, or linseed oil; or may be provided by using a lubricating compound sold under the trade name oil-dag which cont-ains carbon particles and oil. The oildag, or -a paste made of lamp black and oil is mixed with a volatile carrier or spreader, such as benzol or benzlne. The volatile carrier 'or spreader should be such that upon its evaporation there remains present in the specimens substantially only the binding oil and carbon.

Dirt solution.

One form of dirt solution, with which the specimens may be impregnated, 1s made in the following manner: A pigment paste is made in the following proportions: To 252 grains of lamp black, add 671.4 grains of olive oil. Nine gallons of benzol and 864 grains of the paste are mixed thoroughly. The lamp black and olive oil should be stirred until a smooth paste is obtained. A little benzol should be added at a time to the pigment paste and stirred until the ben- Zol and paste are thoroughly incorporated. After about one-half gallon of benzol has been mixed with the pigment, the remainder of the benzol should be added and the whole mixture well stirred. The mixture is allowed to set for not less'than three days. The mixture should be stirred or shaken at least three times each day, during the three days in order to dissolve the pigment paste in the benzol. If less than this amount of dirt solution is made up at one time and used to treat the specimens, the specimens will not be impregnated sufliciently uniform to produce an accurate result by test, even though the same proportions are used.

Sailing.

The samples can be soiled by manually dipping them in a vat of dirt solution, or the dirt solution can be placed in a washing tub of any suitable laundry machine, and the specimens added, the washing machine being operated in the same manner as though clothes were being washed. If the machine is of the rocking tub type, the period of operation is about thirty minutes. The specimens are then removed from the dirt solution and hung up to dry. If, after drying, the specimens are found to be too light, the specimens are put back into the dirt solution and the washing machine is again operated to impregnate the specimens with more dirt. This should be done not later than one day after the specimens were first treated. Dirt solution that has been mixed up for three or four weeks is of better quality for treating the specimens than that which has been mixed for only a few days before using. A few more specimensthan are required for the test are made to provide for replacement of specimens that may prove unfit. However, specimens should not be made up for more than a few days before using, inasmuch as their photometric readings do not remain constant. A lesser percentage of dirt can be removed from an old specimen than from a newly prepared specimen. Therefore, all specimens should be used within a few days after being prepared. Not more than sixty specimens should be treated with nine gallons of dirt solution. One of the pieces of muslin should not be impregnated with dirt; but should be left clean and white to serve as a master specimen, and for denoting 100 percent clean.

1 serene Photometric readings.

The specimens to be examined for light reflecting ability are mounted singly on a black background 20, as indicated in Fig. 5 of the drawings. A projector 21 is used to throw a beam of light on the specimen. This light is reflected into a photometer 22 which is adapted to give a reading of light intensity in foot candles. The amount of light shown in foot candles on the photometer scale is inversely proportional to the amount of dirt in the specimen from which the light is reflected. A piece of cardboard with a round hole preferably about one inch in diameter is used in place of a slide in the projector 21. The projector and photometer are so arranged with respect to each other that the diameter of the spot of light projected on the specimen is as near as possible the diameter of the focus of the photometer, but slightly larger, so that substantially all of the light reflected from the specimen will be directed into the lens of the photometer. The light that does not strike the specimen is substantially absorbed by the black background 20.

The master specimen, denoting 100 per cent clean is first placed in position on. the background 20, and the intensity of the projector lamp is varied to obtain a photometric reading of about 5.6 foot candles, which forms a convenient working basis. The rheostat in the photometer lamp circuit may be varied in order to obtain a close current adjustment, but it is preferable to vary the current in the projector lamp circuit. Great accuracy is required inasmuch as a variation of .01 ampere is sufficient to make the test inaccurate.

The impregnated specimens are then placed on the background. 20 and photometric readings taken of the same. When taking readings of soiled specimens, the master specimen should be frequently read as a check to determine whether the photometer is still giving correct readings. No reading of the photometer will.be correct if the photometer does not give a reading of 5.6

foot candles for the master specimen. For the sake of accuracy, it may be advisable to take a second set of readings of the specimens, but the difference in readings should not vary more than .1 foot candle. photometer and projector should be turned on at least thirty minutes before any readings are taken in order to heat the resistance and thereby cause the current consumption to remain constant. As the readings are taken, the same should be recorded by the operator and the specimens consecutively labeled for purposes of identification. Those specimens giving a reading between a given range of limits, for example, between 1.512

The

neonate and 1.9 foot candles representingtrom 27 .per cent clean to 34 per cent clean, respectively, should be grouped together in sets representing substantially the same per cent clean and the other specimens discarded.

Washing of impregnated specimens.

The water used in washing the specimens in various washing machines submitted to the test should be the same in hardness, soap content and temperature. The water should be at least soft enough to maintain a suds for approximately four minutes. The water is heated to a temperature slightly in excess of 120 F, and the required amount of water, as specified by the washing machine manufacturer, is placed in the washing tub, and allowed to cool to 120 F. When this temperatureis reached, the test should be started immediately. This method heats the washing tub so that there will not be a rapid radiation of heat after the test is started, due to placing hot water in a cold tub. Soap in the proper proportions is added, and when a proper suds is obtained, a load should be added to the washing tub, in order to secure a true washing action. In addition to a few of the impregnated specimens of substantially the same photometric measurements, the load should include about three sheets of muslin, approximately 6 feet by 6 feet in size. After the washing machine has been operated for about twenty minutes, the specimens should be removed from the washing tub, wrung out, rinsed in lake-warm water, wrung out, then rinsed in cold water, wrung out and hung up to dry. After the 1.6703 (average of foot candles of specimens as a unit) specimens become thoroughly dry, photometric readings should be taken of the same in the manner indicated above.

flomputation of results. I

The master specimen represents 100 per cent clean, and its photometric reading is 5.6 foot candles. The impregnated specimens are less than 100 per cent clean, before being washed. Their photometric readings ranging from 1.512 to 1.9 foot candles, equals the per cent clean the treated samples are of the master specimen. if more than one photometric reading is taken of each specimennbefore washing, the average reading is the one used. The average reading of the few specimens which are washed at one time, is also determined. This average represents the few specimens as a unit. The per cent clean representing the test, before and after washing, is obtained from this average. For example, considering that three specimens are impregnated at one time:

Readings in foot candles after impregnation.

General average of average of Specimens A, B, and (3:1.6'203 foot candles. Per cent clean before washing:

5.6000 (foot candles light reflected by master specimen) T After the washing of the specimens has been completed, photometric measurements are taken of the specimens and the result computed in the same manner as indicated above, to determine per cent clean.

The difierence between the per cent clean after washing, and the per cent clean before washing, is ,dirt, in per cent removed. This dirt, in per cent removed, indicates the cleansing ability of the selected washing machine. The percentages of dirt removed by various machines are used as a basis for comparison of the cleansing ability or" the machines.

While the method herein shown and de scribed, constitutes a preferred embodiment of one form oi invention, it is to be understood that various changes and alterations may be made in the shape, size, and proportion of the elements therein without departing from the spirit and scope of the invention.

What is claimed is as follows: 1. The method of testing the cleansing ability of a laundry machine which ineludes soiling a sample of cloth, and in 7 taking photometric measurements of the light reflecting ability of the sample before and after washing in the laundry machine, the standard of comparison being the light reflected by an unsoiled sample of preferably the same piece of cloth representing one hundred per cent cleanliness.

2. The method or' testing the cleansing ability of .a laundry machine which includes soiling a plurality of samples of cloth with substantially equal amounts of dirt solution, and in taking photometric measurements of the light reflecting ability of the samples, washing the samples with a load in the laundry machine, and in taking photometric measurements of" the light refleeting ability of the samples, the standard ct comparison being the light reflected by Elli) an unsoiled sample of preferably the same piece of cloth representing one hundred per cent cleanliness.

3. The method of testing the cleansing ability of a laundry machine Which includes soiling to equal extent a plurality of samples of cloth with a dirt solution, taking a plurality of photometric measurements of the light reflecting'ability of each sample before and after Washing in the laundry machine, and determining a general average of the average readings of a plurality of samples to give a unit average, the standard of comparison being the light reflected by an unsoiled sample of preferably the same piece of cloth representing one hundred per cent cleanliness.

4c. The method of testing the cleansing ability of a laundry machine Which includes soiling to equal extent a plurality of samples of cloth with a dirt solution, taking a plurality 0t photometric measurements of the light reflecting ability of each of the sam ples, determining a general average of the average readings of plurality of the samples to give a unit average, Washing a plurality of the samples in the laundry machine, taking a plurality of photometric measurements of the light reflecting ability of each of the samples, determining a general average of the average readings of the samples to give a unit average, the standard of comparison being the light reflected by an unsoiled sample of preferably the same piece of cloth representing one hundred per cent cleanliness.

5. The method of testing the cleansing ability of a laundry machine which includes soiling to equal extent a plurality of samples of cloth with a dirt solution, drying the samples, taking a plurality of photometric measurements of the light reflecting ability of each of the samples, determining a general average of the average readings of a plurality of the samples to give a unit average, Washing a plurality of the samples inthe laundry machine, drying the samples, taking a plurality out photometric measurements of the light reflecting ability of each of the samples, determining a general average, the standard of comparison being 6. The method of testing the cleansing ability of a laundry machine which includes Selling to equal extent a plurality of samples of cloth With a dirt solution, rinsing and drying the samples, taking a plurality of photometric measurements of the light. reflecting ability of each of the samples, determining a general average of the average reading of a plurality of the samples to give a unit average,\vashing the samples in the laundry machine, rinsing and drying the samples, taking a plurality of photometric measurements 01 the light reflecting ability of each of the samples, determining a gen-- eral average of the average readings of the samples to give a unit average, the stand ard of comparison being the light reflected by an unsoiled sample of preferably the same piece of cloth representing one hundred per cent cleanliness.

7. The method of testing the cleansing ability of a laundry machine which includes soiling to equal extent a plurality of samples of cloth with a dirt solution, rinsing and drying the samples, taking a plurality of photometric measurements of the light refleeting ability of each of the samples, determining a general average of the average readings of a plurality of the samples to give a unit average, washing the samples With a load in the laundry machine, rinsing and drying the samples, taking a plurality of photometric measurements of the light reflecting ability of each of the samples, determining a general average of the average readings of the samples to give a unit average, the standard of comparison being the light reflected by an unsoiled Sam-- ple of preferably the same piece of cloth representing one hundred per cent clean-- liness.

In testimony whereof I hereto aiflx my signature.

RALPH L. LEE.

Witnesses J. W. McDoNALn, lVARREN SOHMIEDING.

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